Question

Seja x²+y²=60.Qual é o valor positivo de x+y, sabendo que xy=20

Answer 1

$x^2+y^2=60\\\\x^2+y^2+2xy=60+2xy\\\\(x+y)^2=60+2xy\\\\(x+y)^2=60+2(20)\\\\(x+y)^2=100\\\\x+y=\pm\sqrt{100}\\\\x+y=\pm10\\\\\boxed{x+y=10}$